P. A. Stabnikov

Saturated Vapor Pressure and Crystal Structure of Bis-(2-imino-4-pentanonato)copper(II)

A comprehensive study of copper(II) bis-ketoiminate including tensimetric analysis of sublimation and structure solution has been carried out. The temperature dependence of saturated vapor pressure over Cu(ki)2 crystals derived by the flow method is expressed by the equation lnP(atm)} = 25.31-13750/T, ΔHsubl = -114.2 ± 1.3 kJ· mole-1,Δ Ssubl =210.2 ± 3.0> J· mole-1 · K-1. Crystal data for CuO2N2C10H16: a=15.143(3), b=16.681(8), c=13.795(32) Å, space group Ccca, Z=12, dcalc = 1.47 g/cm3, R=0.029. The structure is molecular and consists of crystallographically independent Cu(ki)2 complexes of two types, one with a cis structure and the other with a cis–trans disordering. The copper atom has a plane square environment of two oxygen and two nitrogen atoms. In the cis isomer, Cu–O 1.938 and Cu–N 1.895 Å; in the disordered complex, all four Cu–O(N) distances are 1.901 Å.

Synthesis and thermal properties of some lithium β-diketonates

Five new volatile lithium complexes were synthesized by reactions of lithium hydroxide monohydrate (LiOH · H2O) with β-diketones, namely, dipivaloylmethane (HDpm), hexafluoroacetylacetone (HHfa), trifluoroacetylacetone (HTfa), benzoyltrifluoroacetone (HBtfa), pivaloyltrifluoroacetone (HPta), and valeryltrifluoroacetone (HVta). The complexes obtained were studied by IR and electronic absorption spectroscopy, mass spectrometry, and comprehensive thermal analysis. The temperature dependence of the vapor pressure, which was obtained by the Knudsen effusion method with mass-spectrometric analysis of the vapor phase composition in the 400–450 K range, was used to calculate the standard thermodynamic parameters of the Li(Dpm) sublimation: ΔH°subl = 45.7 ± 1.7 kcal mol−1 and ΔS°subl = 77.9 ± 4.0 cal mol−1 K−1.

Packing of complexes and intermolecular interactions in the crystals of volatile palladium(II) β-diketonates. crystal structure of palladium(II) benzoyltrifluoroacetonate

This paper reports on the synthesis and crystal structure analysis of palladium(II) bis-(trans-benzoyltrifluoroacetonate). Crystal data for PdO4C20F6H12:a= 4.748, b = 22.237, c = 9.410 Å, P = 105.44° Z = 2, space group P21/c, dcalc. = 1.86 g/cm . CAD-4 diffmctometer(MoKa), heavy atom method, R = 0.041 for 986 reflections. The structure is molecular; the planar molecules are stacked. The Pd atom is surrounded by a square of four O atoms (Pd−O = 1.97 Å, chelate angle 94.4°); Pd is involved in additional intemctions with the Cγatoms of two neighboring molecules (Pd...Cγ= 3.44 Å). The molecular structure of palladium β-diketonate complexes, molecular packing in crystal, and intermolecular intemctions are considered. The van der Waals energies of the crystal lattice are calculated. The results are compared with the experimental values. In the structures of palladium( 11) β-diketonates, three groups of crystals are isolated: one group with 2 nearest-neighbor interactions (stacks), the second with 4 nearest-neighbor interactions (two-dimensional nets), and the third with 1 nearest-neighbor interaction (dimers). The latter are characteristic of the cis-complexes. The intemctions with 10–12 nearest neighbor molecules determine the energetics of the whole crystal. The high volatility of Pd(hfa)2 is explained by the weaker intermolecular contacts between stacks in crystal.

Parameters and Form of the Mössbauer Spectra of Iron(III) β-Diketonates: New Data

Mössbauer spectra have been measured at 295 and 78 K for ten 57Fe-enriched iron(III) β-diketonates differing in the type of radical in the chelate ring. Since the literature data for compounds of this class are incomplete and contradictory, a repeated analysis of spectrum shape and parameters has been performed. The chemical shift and quadrupole splitting are virtually independent of the type of radical in the chelate ring whereas the line width and asymmetry exhibit a pronounced dependence on the temperature and composition of the compounds. The available concepts on the nature of quadrupole splitting and relaxation mechanisms determining the lineshape for the given compounds are refined. It is concluded that electron spin relaxation is “longitudinal” or “transverse” relative to the principal axis of the electric field gradient in different compounds.

Analysis of the Probability of the Mössbauer Effect in Iron(III) β-Diketonates

The probability of the Mössbauer effect f′ has been evaluated and the Debye temperatures of intermolecular vibrations θM at 295 and 78 K have been determined for ten Fe(III) β-diketonates, which are complexes of molecular type. Variation of θM with temperature and molecular mass M has been found; in the latter case, θM decreases as M increases. As a result of this antibatic change in θM and M, the effect of a decreased energy of intermolecular interaction dominates the effect of increased molecular mass, and f′ decreases in conformity with the prediction provided by the molecular crystal model.

Crystal and molecular structures of bis-(5-methyl-5-butoxy-hexanedionato-2,4) Copper(II) and bis-(2,2-dimethyl-5-cyclohexyl-pentanedionato-3,5) Copper(II)

Two new volatile complexes of Cu(II) containing methoxy groups were studied in a combined X-ray diffraction investigation of the mono- (KUMA automatic diffractometer, MoKα radiation) and polycrystals (DRON-3M, CuKα radiation). The structures are molecular and consist of the trans-complexes of bis-(5-methyl-5-butoxy-hexanedionato-2,4)copper(II), C22H38CuO6, and bis-(2,2-dimethyl-5-cyclohexyl-pentanedionato-3,5) Copper(II), C28H46CuO6. The crystal data of C22H38CuO6: a = 8.939(1), b = 8.887(2), c = 8.326(1) å, α = 107.92(2), Β = 108.15(1), γ = 85.52(2)‡, space group P1,V= 597.9(2) å3, Z = 1, dx = 1.283 g/cm3. The crystal data of C28H46CuO6: a = 18.625(3), b = 16.126(2), c= 13.613(3) å, Β = 132.19‡, space group P21/n, V= 3029.3(9) å3, Z = 4, dx= 1.189 g/cm3. In both cases, the square planar environment of the Cu atom with Cu...O distances of 1.90 å is completed by interactions with two carbon atoms of the terminal groups of the two neighboring molecules at Cu...C distances of 3.66 å (average).

Crystal structure oftrans-bis-(2,2,6-trimethyl-6-methoxy-5-iminoheptan-3-onato)copper(II)

A new volatile N,O-chelate complex of Cu(II) containing a methoxy group was studied by X-ray diffractometry (KUMA automatic diffractometer, MoKa radiation for single crystals and DRON-UM1, CuKa radiation for polycrystals). The structure is molecular and consists of transcomplexes of bis-(2,2,6-trimethyl-6-methoxy-5-iminoheptan-3-onato)copper(II). The structure was refined in an anisotropic approximation using 2426 independent reflections to R = 0.048. Crystal data: a = 13.426(2), b = 9.566(2), c = 19.562(4) Å, Β = 90.72‡, space group F21 /n, V = 2512.2(8) Å3, Z = 4, dcalc = 1216 g/cm3. The squareplanar environment of the copper atom with distances Cu-O = 1.938 and Cu-N = 1.912 Å is completed to pyramidal by interaction with the oxygen atom of one methoxy group of the neighboring molecule at a distance of Cu...O = 2.81 Å.